Has anything changed in the room you keep her in?
Does she do this when you are present in the room or out of the room?
Does she do this if you sit near the cage and talk to her, read, watch tv etc?
The reason I ask, is because my grey will make a very loud smoke alarm/home alarm door opening sound as well when he wants our attention whether we are in the room or not. He will not stop until one of us either decide to sit next to his cage or let him out. Ignoring him does not matter, the sound will continue until he decides to eat something, play a little or get a little shut eye, then they will resume.
Also, this is not a contact call, it is a sound of annoyance, desperation or exasperation.
It could just be, that this precious soul has come to like you and your attention.